Programable Digital Temp Gauge

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big d

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very similar to mine except this is for kpa but for temp they are the same.4 alarm lights across the top and very programable.
this info is mainly for jayse who i discussed with last night.
anyway the dealer is instrotech
65/119 belair rd
torrens park
sa 5062
if your in the area check em out

no idea brenton as its a gift from a sparky mate but i believe a similar brand is in the vicinity of $ you need a rtd to run it and these are over $100.
either way they are an expensive set up but as it was offered to me i couldnt say no as my mate was keen when the word beer was mentioned ;)
Big D,
Looks nice. Could you tell your mate I have some excess BEER too :)
Kind of funny Big D, all I've been doing for the last 4/5 days when on the internet is trying to learn about PIDs, more specifically trying to find a nice one on US ebay to buy and then how I'd go about running it. Maybe over kill but I certainly love gadgets, and certainly enjoy educating myself about various bits and pieces like this so I'm still pretty keen to get one.

God this stuff (info) is so hard to find in Oz though. I've been looking at options for inputs and generally your looking at thermocouples, RTDs, Linear voltage inputs, and if your lucky you may be able to get a NTC thermistor input option as well. Well, the platnium RTDs sound pretty good but do you think I could find one in Oz with a price. Nope. So about a $100 buck, thanks Bigd for that one-guess I might give the RTD a miss, bummer.

I'm thinking if I go this option I'm either going to get a thermocouple from the ebay in the states or, if my research pans out I may be able to use an LM35 Precision Celcius Temperature Sensor (~$8), I may possibly need to build an ampilfier so the PID can use the input but it looks as though most PIDs may be able to direct read an LM35 producing 10mV/degree C.

Any of you guys care to give me your thoughts or share your knowledge in this aspect, particularly the use of an LM35 as direct input to a PID. I know there can be issues with using long leads to the LM35, so maybe a thermistor is another possibility (also dirt cheap ;) at about $2).

I think I'm going to end up building myself a digital thermometer or two using panel mounted digital voltmeters and three or more temp probes that I just select by using a switch, centring around the use of LM35's or thermistors. This comes after finding a couple of brewing sites talking about using thermistors in the brewery.

Cheers, Justin
use a picaxe with a dallas digital temp IC, the IC are say $5-$10, and on paper within 0.2deg C, long leads are not such a issue as the Anolog to Digital is done in the chip and the pic axe can talk to it with the "get temp" command

The pic axe (the smallest chip 08M is say $5 - cheap controler) or move to 18X where you have a heap more code space etc

you can get a datalogger and the LCD "kit" thats basicly plug and play although you get up in price a bit more

Programing is in "Basic" format and shouldn't take long to master

microzed in syd? sell all of this

note: these are not of the shelf solutions but component level, and or kits

P.S not sure how many digital inputs there are (different on each chip) but you can add aditional LM35, Lm34, Lm335 etc on a anolog input and use a output for things like turning heat on or off, pumps etc

and as normal power kill blah blah exp with beer and liquid so dont play with mains voltages....... esp when pissed
Oh man, Ben your just getting me in deeper :eek: . I'd love to have a chat to you about this right now but I'm going to have to do a bit of research on these puppies first so I don't have to ask dumb questions. My electronics knowledge is limited, so I'm going to read up and see if this is going to be a viable idea to follow. That's heaps for the idea and direction though, I'm stoked :D.

A quick one though, how easy is this BASIC programing to master coming from zero experience, doesn't look that bad? I just had a quick look at the starter kits from microzed and a quick browze over the site. Noticed they have project boards, the works. Looks exciting :). Guess I might PM you, if that's alright, and see if you can answer a few more specific questions for me. But I won't trouble you until I wise up a bit.

This is funny because all this interest in building a digital thermometer started from just using a DMM and a thermistor and a graph, now it's developing into a monster. But I love it. Who has time to work these days when there is so much other cool stuff to learn :).

Cheers, back soon. Justin
no worries re: PM'ing me

As from a Zero programming knowledge then I cant say, as some people can pick up programming easy, others just cant think in that manner

that said, the picaxe was started up for school kids to gain interest in electronics, so I think most should be ok with it ( how ever its not as quick and simple as buying it off the shelf, but might be cheaper and more fun!)

I have just started using these and although I work with electronics I am not a software person and I find the code easy enough.

It is designed to limit the complexity and therefore code remains semi simple

Silicon Chip had and still are running about one article a month on this set of micro's as for the hobbyist there great
If you get stuck i should be able to help with any BASIC programming, haven't touched it in years admittedly, but it's a damn simple language (compared to c# it's like k+k vs AG).
But seriously, if you can figure out how to wire up PID you should be able to learn enough BASIC for your needs.

It has been a While but I am back.

Here is some tech for you

The unit you are talking about although displays KPA (pressure) This unit is calibratable for any analog input.

It is an instrumentation unit that uses either a 0-10V signal or 0-20/4-20ma Signal.

To use this unit for Temp you will need a TDR (temperature dependant resistor) often called RTD's and a Process transmitter to change from RTD to 4-20ma.

This is where it becomes expensive.

The best unit is pricy. Jayce and I use OMRON. They use a direct RTD input. Have 4 outputs 2 user and 2 Alarm. and will also control a 4-20ma PID output
and I would assume there will be tolerances introduced with the additional circuitry/conditioning and singnal conversion etc, unless you go for the ready unit as you point out costing more.
Whats the temp accuracy on a RTD?

there is a national semiconductor device... Lm 3# somthing thats a current out, that rings a bell, maybe this could be used
You would be quite surprised ben.

Instrumentation has come along way very fast the last few years.

The ready made unit retails for around $300 and is calibrated to whatever temp input you like.

The OMRON can use either RTD or Thermocouple.

Although looking at 4-20ma doesnt look very fine the controlers are 32bit therefore looking at like 6 decimal places.

You can set the hysterysus to suit your appliance so as much or as little overlap as you like.
Guys - talk to Doc - i think he uses/has programed something similar...
sounds good but i cant spend the $300 :(

thats another thing worth thinking about, using the picaxe etc you most likly... infact you wont get the same control on temp as with the PLC and their crazy indepth software to stop overshoots and predicting and adopting to systems etc
If you want to go the extent of a PIC you may as well go to PC control.

The Best PIC will do but you need to worry about calibrating it you need to worry about a display an adjuster and programming. I have played with picks and they are good but for $60 you can purchase a kit with all parts to build a parallell interface for your computer with 8 digital in 8 digital out 1 analog out and 4 analog in. You can even daisy chain up to eight and the software is piece of piss. it even comes with examples.

I am working on doing this myself however still using the OMRON temp controllers for their reliability and accuracy.
indeed there is another option, i did some homework on this and again used the dallasdigital ic's

any links to this set up Randy, sounds interesting

however i think i will use the picaxe due to ease for my HLT (maintaining its temp) and most likly the mash also as its fun :) and i dont really want the pc out with the beer.

and i also plan to use these simple chips to control things like the fermenter temps (pumping chilled water) and even the pump to chill the font where i maynot want the computer on all that time

but i agree this sounds like a very good option and might be best for some
Here is another option if you are looking at burning some cash :) when I run out of things to upgrade I may get something like one of these :)

Of only I could get some actuated valves for under $30 the whole shooting match could be automatic and I could watch tv while it brews my beer :p
i know nothing about gas but i heard some guys using car gas valves or somthing to control there temp in gas systems.... they said about $20
Ben said:
indeed there is another option, i did some homework on this and again used the dallasdigital ic's

I use the Dallas DS1820 temperature sensor chips which have a digital output. I have used PIC microcontrollers to monitor these (still have one of these as a thermostat for my fridge). You don't have to adjust these chips or calibrate them, they are all preset and accurate to within 0.5C. The code for this is in 'C', as it is a bit better to write in than basic on the PIC chips IMO.

I am now using DS9097U-009 devices that connect the DS1820's to the serial bus of a laptop -

I have written software in VB to monitor the temperature and control the heat stick in the HLT. It has been around 90% done for a bit over 9 months now.

If anyone wants more info, PM me.


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